Akō Castle (赤穂城, Akō-jō) is a flatland Japanese castle located in the city of Akō, Hyōgo Prefecture, Japan. Built by the Asano clan in the Edo period, it was the center of Akō Domain in western Harima Province. The castle was designated a National Historic Site in 1971, with the area under protection expanded in 2003. Within the castle grounds is the Nagayamon gate to the residence of Ōishi Kuranosuke, the karō of the domain under Asano Naganori. The house itself no longer exists, but its location has a separate National Historic Site designation. Both the Honmaru Garden and the Ni-no-Maru Gardens have been restored to an approximation of their appearance in the Edo period, and are collectively designated a National Place of Scenic Beauty in 20212.